The present invention relates to a method for trimming loose threads on circular knitting machines. More particularly, the invention relates to a method for trimming loose threads produced by the formation of a particular pattern on a ground or base fabric, so as to avoid leaving loops on the reverse side of the manufactured fabric.
As is known, in the field of circular knitting machines, when a particular pattern is produced on a ground fabric, it is necessary to knit in threads that are different from the ground fabric and are carried on the needles by means of specific devices.
In order to achieve a better effect of the knitting process, it is necessary to cut the threads that are knitted in in addition to the ground fabric when such additional knitted-in threads have finished forming stitches. Substantially, in order to avoid leaving any loops on the reverse side of the manufactured fabric, the knitted-in threads added to the ground fabric must be cut or trimmed at the point where the thread has stopped being knitted, i.e., has no longer been knitted in.
Generally, programming of the circular knitting machine starts from a graphic environment that adopts particular conventions based on so-called special colors. Each special color corresponds to a given type of very specific knitting of the machine and produces a predefined link to the physical apparatus that performs the knitting. Knitting is thus performed by the apparatus that produces a particular effect on the fabric.
The meaning of so-called special colors can be modified according to the type of machine and according to the configuration that the user wishes to set on such machine. Such configuration can vary for any type of pattern and for any kind of item.
Generally, a specific special color is associated with the ground fabric and the other special colors are added in order to describe the intended effects and the knitting on the fabric. These effects, as mentioned, are obtained by knitting into the fabric threads that are different from the ground thread and are knitted by means of specific devices, which change when the special color changes.
Therefore, on the basis of these simple machine programming rules, knitting constituted by the so-called ground fabric and by a superimposed xe2x80x9cembroideryxe2x80x9d is formed, during programming, from a pattern that is provided with only two special colors that are suitable to identify the two different processes: a so-called ground color and a so-called pattern color.
The pattern effect on the fabric is obtained, as mentioned, by knitting in alternative threads in the ground fabric, and in order to obtain a better effect in the knitting process it is possible to cut the threads when they have finished knitting, i.e., they have finished forming stitches. Cutting a thread that ceases its task is also known as trimming.
Trimming can occur, due to production reasons linked to the mechanical structure of the machine, only in certain conditions, one of which allows to trim the thread only when a certain number of needles has passed after the end of its knitting.
Trimming is performed in any case at the point where said thread has ceased knitting.
Currently, if one wishes to perform trimming, in order to eliminate therefore the loose thread, the operator must check that the distance, calculated in terms of the number of needles at the end of the knitting of the thread to be trimmed, is appropriate for trimming on that given type of machine.
Once this check has been performed, the machine operator must change the type of knitting, for example by changing the drop, or by changing the thread guide, so that if the calculated distance is not appropriate for trimming it is still possible to perform said trimming.
These operations obviously entail an expenditure of time and also require the presence of a highly specialized operator.
The aim of the present invention is to achieve a method for trimming loose threads in circular knitting machines that allows to perform automatically those process corrections that the operator can perform on the machine in order to be able to perform the intended trimming of the loose threads.
Within this aim, an object of the present invention is to provide a method for trimming loose threads in circular knitting machines that allows the operator to be sure that if trimming of the loose threads is possible, it is actually performed with an automatic modification of the knitting process that must be imparted to the circular knitting machine.
Another object of the present invention is to provide a method for trimming loose threads that allows to perform an automatic check of the possibility to trim the loose threads.
Another object of the present invention is to provide a method for trimming loose threads in circular knitting machines that is highly reliable, relatively simple to provide and at competitive costs.
This aim and these and other objects that will become better apparent hereinafter are achieved by a method for trimming loose threads in circular knitting machines, characterized in that it comprises the steps of:
starting from an initial pattern and on the basis of a given type of circular knitting machine, if one wishes to trim the loose threads, measuring a distance between the needles of the same color on a same row in order to check whether said distance is at least equal to, or greater than, a minimum distance that allows to perform trimming of the loose threads;
if said distance is shorter than said minimum distance, replacing a portion of said pattern with at least one special color that identifies a different type of knitting process for said portion of said pattern, to be performed on said circular knitting machine;
modifying said pattern on the basis of said replacement of said portion of said pattern;
producing an advancement by a number of rows equal to the number of drops of the knitting machine that are active; and
encoding the pattern with the modifications, in order to perform the knitting process.